Air heater



Sept. 27, 1966 K. s. JENSON ETAL AIR HEATER 4 Sheets-Sheet 1 Filed Dec.31, 1965 1 MOW U 7);

s gll p 27, 1 K. s. JENSON ETAL 3,274,989

AIR HEATER 4 Sheets-Sheet 2 Filed Dec. 31, 1963 Sept. 27, 1966 K. s.JENSON ETAL 3,274,989

AIR HEATER Filed Dec. 31, 1963 4 Sheets-Sheet 5 ja /Q Sept. 27,1966

K. S. JENSON ETAL AIR HEATER 4 Sheets-Sheet 4,

Filed Dec. 31, 1963 United States Patent 3,274,989 AIR HEATER Kenneth S.Jensen and Frederick W. Suhr, Wisconsin Rapids, Wis., wsignors toPreway, Inc., a corporation of Wisconsin Filed Dec. 31, 1963, Ser. No.334,693 Claims. (Cl. 126-110) This invention relates to air heaters andespecially air heaters for heating air within a building or roomthereof.

Air heaters of the type installed and used within living areas ofdwellings have in recent years come more and more into use. Such heatersinclude space heaters as well as heaters for heating the entiredwelling. These heaters are often constructed with attractive exteriordesigns because they may be installed directly in living quarters ratherthan in a cellar space or other isolated space. However, because of theheating function of the air heater, often a hot surface is provided inthe heater which may constitute a hazard when the heater is installedand used in living quarters. Inadvertent contact with such a hot wallmay result in a severe burn or discomfort.

Further, such an air heater is conveniently installed with an outletthrough a wall or ceiling structure. Additional hazards may be createdby leakage of vent ducts. Also, where a burner is employed for heatingpurposes, the efliciency of the heater may be decreased by flow ofexhausted gases back into the burner intake.

The heat within the air heater structure may also damage electricalcontrol systems or the like. Often it is difiicult to gain access tointernal working parts and the electrical system for servicing,especially where a separate flow system is provided for the combustiongases and air is circulated in heat exchange therewith for absorbingheat. Further, overly complex mechanisms are often employed fordirecting heat from the air heater to a particular chosen area of a roomor building by deflectors or the like.

It is a general object of this invention to provide new and usefulimprovements in air heaters which may be installed within livingquarters. Particularly, it is also an object of this invention toovercome or alleviate problems such as those discussed above.

It is a more partioularobject of this invention in one aspect thereof toprovide a household air heater with an outer casing wall insulated fromthe internal heat by a flowing blanket of air.

Still another object is to provide a new and useful air heater of thetype operated by flowing air in heat exchange withcombustion gases in aseparate flow system wherein all parts of both flow systems are easilyand conveniently available for servicing or the like.

FIGURE 1 is a perspective view of a form of air heater of thisinvention;

FIGURE 2 is a view looking into the air heater of FIGURE 1 with thefront door removed;

FIGURE 3 is a section through the air heater of FIGURE 1 along lines 3-3of FIGURE 2, with the air heater mounted on and supported by a wall of abuilding; and

FIGURE 4 is a view of a portion of the rear of the air heater of FIGURE1 showing a form of venting arrange'ment; and

3,274,989 Patented Sept. 27, 1966 FIGURE 5 is a side view and partialsection of the air heater of FIGURES 1-3 with another form of ventingarrangement for use with a chimney.

In general, the embodiment of air heater illustrated in the drawings isof the type in which air is drawn in from a room or building to beheated and the air is passed in heat exchange with a combustion chamberwherein fuel is being burned. The heated air is then discharged back tothe room or building and air is continuously passed through the heaterwhile on, for heating purposes. The air for supplying the burner isdrawn in through a separate intake system from outside of the room orbuilding and the combustion gases and fumes are exhausted exteriorly ofthe room or building.

Referring to the drawings, as seen generally in FIGURE 1, the embodimentillustrated includes a hexahedral casing having outer walls on each ofthe six sides thereof. As seen in FIGURES 1-3, the outer side walls 12and 13 and top wall 14 are formed of a single sheet member 15 and haveinwardly turned flanges 16 overlapping and abut' ting peripheral edgesof an outer sheet member 19 of a rear wall 20. The front edge of sheet15 is folded inwardly within the casing at 21 and, thence downwardly inan inward flange 22 providing a recess flange or angle member 23, thepurpose for which will be seen hereinbelow. Flange 22 forms one leg ofthe angle member 23, the other leg terminating at fold 21. The rear wall20 includes sheet member 19 and an internal sheet support member 24'facially secured thereto and terminating at its upper end in achannel-like configuration at 25 for adding rigidity to the upper rearedge of the casing.

The bottom wall 26 of the casing includes a bottom sheet 29 abuttinginwardly turned flanges 30 of sheet member 15. Sheet 29 is backed withan inner sheet 31 and secured thereto, sheet 31 having a rearwardchannellike portion 32 which is secured by one channel leg to sheet 24.A rear flange 33 of sheet 29 turns upward overlying sheet 19 of rearwall 20, sheet 19 being backed by brace or sheet member 24 which issecured to both flange 33 and sheet 19. Inner sheet 31 is secured to theupper faces of flanges 30 and backs the abutting joint between flanges30 and sheet 29.

The front edge of sheet 29 also terminates in a recessed angle portion23, the bend at 21 clam-ping and holding the front edge of sheet 31between the opposing surfaces of sheet 29. in forming the angle 23.

A second casing Wall structure is provided generally enclosing acombustion and air heating portion 34 of the illustrated air heater,except for the air intake and outlet passages thereof. The second casingwall structure is spaced inwardly from the outer casing structure todefine a flow path 35 between the inner and outer casing structures incommunication with an air intake chamber 36 for delivery of air to theheater from the room to be heated by the heater. The flow path 35insulates outer casing top wall 14, rear wall 22, bottom wall 29, andside wall 12 from the combustion and air heating portion 34 of thedevice so that these walls remain cooler than otherwise. End 13 and thefront of the illustrated air heater include air inlets and outlets,respectively, for circulating air through the heater and are notprovided with the insulating air flow path, is. not backed by theinwardly spaced inner casing.

The inner casing, indicated generally at 39, is composed of a pluralityof sheet members secured together by overlapping flanged edges to forman enclosure. spaced inpurposes.

rest on or be welded to channel member 32. Channel members 25 and 32extend the length of the rear wall 19, blocking air communicationbetween the portion of passage 35 along wall 19 andthe portion ofpassage35 along top wall 14 and bottom wall 29.

Casing 39, it will be noted, is open at the end dis posed toward end 13of the outer casing of the device.

A sheet metal member 42 is configurated to .definean air chamber 44 andhas down-turned or inwardly turned flanges 43 along the front and rearedges thereof. Rear flanges 43 are secured to the interior surface ofthe rear wall of casing 39. Air chamber 44 is the intake chamber forreceiving air to be used by a burner 45 mounted by suitable means withinchamber 44. Burner 45 is illustrated in the form of an automaticgun-type? power burner, a type of burner used in central heating plants.Such a burner is electrically controlled for ignition and shut-off andis capable of drawing surrounding air and creating suflicient powerdraft for burning of the fuel, in this case, oil. The oil is; introducedto' the burner in normal manner by feed lines (not shown), flame andcombustion gases being discharged from burner 45 through outlet passage46 into a pot portion 49 of a furnace 50.

defining a combustion chamber internally thereof. Furnace 50 is providedwith a service port c'over 51 bolted in place .as at 52. The combustiongases from combustion chamber 50 are passed through an outlet ductorfpassage 53 terminating in tubular projectionr54 for exhausting such'combustion gases from the device. Force for draft at the burner and forexhausting the gases'is provided integrally in the burner structure.

Upstanding from sheet 42 is a sheet member 55 extend mg the depth of theair heater casing, and, with sheet'42 t and casing 39 defining airintake chamber 36 to the left thereof, as viewed in FIGURE 2, asachamber separate from the air heating chamber 34. The sheet is secured,

along its top edge to flange 56 projecting downward from the portion ofcasing 39 spaced inwardly from wall 14.

The lower edge of sheet 55 is secured by'flange 59 to sheet- 42 and therear edge is secured to the rear wall of casing 39. An opening 60 isprovided through sheet 55 surrounded by a skirt 61 defininga throatopening 61 extending inwardly into chamber 34; Mounted within the throatmember 61, coaxial therewith, is a blower or fan having a plurality ofblade members 62 driven by a motor 63 suitably mounted in chamber 36 bybrackets (not shown).

The front wall of the illustrated air heater device is shown generallyby reference numeral 64; Vertical and.

horizontal brace members'65, each having a cross-sectional T-shape, areinterconnected across the front of the casing and are secured at theirends to each other or to angle legs 22, "providing. continuation of therecessed channel members 25 and,=32 from communication with,

flange or leg 22 vertically spanning the front and horizontally spanninga portion of the front, forming a frame structure of front wall 64.A'door 69 is mounted by hinges 70 to the rearward folded portion ofwall- 13 ad jacent fold 21. Door 69 is provided with a handle 71 and isopenable and closable on hinges 70. Door'69 is provided with asnap-catch (not shown) of conventional design for securing the door inclosed position, but releasable for opening the door. The inner surfaceof door 69, when door 69 is closed, is flush against and abuts angle 43and the forward edge of plate 55 to generally seal chamber 36 fromchamber 34 except-via port 60. The inner surface of door 69 also sealsolf and'forms the front wall of combustion air chamber 44, preventinguse of appreciable amounts of room air for combustion and may includeinsulation between the two walls, if desired. Door 69 is provided forgaining access to the Door 69 may conveniently be double-walled mountedon a Wall of the room. Box or electrical system I 68 is mounted on wall42a in chamber 44 and isthereby isolated from the hotter chamber34;-also,' sheet member 42, of which wall 42a is a portion blockssubstantial .heat exchange between the outlet chamber 53 from furnace 59and the electrical system. With door 69 closed the peripheral, edgesthereof arefacially disposed against flanges 22 and an arm of T-framemember 65. Thus, door 69 is used to close and substantially seal aplurality of chambers from each other without employing permanent sealsof compositions'which may deteriorate with Front wall 64 also includes apair of grillpanels V illustrated as being of generally squareconfiguration and use.

shown generally by reference numeral 72. Each grill panel includes aframe 73 supporting a plurality of parallel vanes 74 having a distinctcurvature for directing air passing therebetween laterally of the vanes,vanes 74 being secured against movement in the illustrated form.

Handles 75 are provided on each of grill panels-72. A

tension spring 76 is provided for each panel72, anchored at one endto agenerally centrally disposed portion of panel 72 and anchored at theother end to the interiorf surface of casing 39 spaced inwardly fromwall 12. Ten: sion spring 76 biases grill member 72 inward against aframework defined by flanges 22 and an arm of T-braces 65. Either orboth of the grill members 72 may be grasped by handles 75, pulledoutward and reorientated in rotation or in multiples of 90. in .rotationand reinserted, spring 76 being sufliciently resilient'to permitwithdrawal of the panels 72 for reorientationthereof and havingsuflicient strength-to retain panel 72 inthei position shown in FIGURE1after reorientation. Thus, by reorientating panels 72 as desired, warmair passing from chamber 34routwardly through 'vanes 74 may be directedupward, downward-or to either side or in any combination of two suchdirections.

Opening of door 69 and removal of grills 72 gives: ac.- cess to thecomplete interior of the device for servicing of component in any of thechambers thereof. The rear wall 'of casing 39 is provided with aplurality of ports 79.

for communicating the air space 35 between casing 39 and rear wall 20with chamber 36. The portion of space along .rear wall 20 is in aircommunication with'the portion of air space 35 along end wall 12,"but isblocked, by

the portions of air space 35 along top wall-14 and bottom wall 29. Theleft edge, as viewed in FIGUREZfofthe 7 rear wall of casing 39 abuts andissecured to sidewall 13 adjacent'an edge thereof; peripherally of thelouvers 77in wall 13." The top and bottom'walls of casing 39 stop shortof wall 13 ;at the lefttin FIGURE. 2.. Thus;

the ends of the portions of air chamber 35lying beneath top and bottomwalls 14 and 29 are open for receiving air, as at reference numeral 80,from the slot ports-defined in wall 13 by louversv 77. It will be seenthat a pressure drop at ports 79,e.g. created by blower 62, would tendto draw air through open ends 80, along walls 14 and 29,"

thence into the portion of air space 35 beneath wall 1 2, into theportion of air space3'5 beneath'rear'wall'20 and through ports 79 intochamber 36. A flowing blanket of air beneath walls 12, 14, 20 and 29 isthereby created. This flowing blanket of air insulates the walls fromthe combustion and air heating chamber portion 34 of the.-

device providing external surfaces. of the thusly insulated wallsiwhichare cool to the touch.

However, the total supply of air'to chamber 36, is not obtained from theinsulating blanket of flowing air. Sub- V stantial amounts of air arealso drawn in through end wall 13. Accordingly, louvers 77 provide aplurality of flow slots through wall 77. Wall 13 is backed by filters 78so that air passing between louvers 77 passes through filters 78 intochamber 36, filters 78 'being held in place by peripheral flangesprojecting inwardly from the top, rear and bottom walls of casing 39 andforming a frame 81, the filters being contained between flanges 81. Thefilters 78, however, do not extend across openings 80 of air space 35..For removal of the filters, door 69 is opened and filters 78 may be slidout from the front of the casing for cleaning, replacing or the like.Reinsertion of the filters will be apparent. Door 69, when closed, sealsagainst the front edge of filters 78.

The filters 78 are packed filters having fibers sufliciently compactedto create resistance to flow into chamber 36 therethrough. With blower62 drawing air from chamber 36, filters 78 serve to provide a pressuredrop across the filters. As a result, air is readily drawn into andthrough air space 35 and into chamber 36, maintaining the blanket of airbeneath the outer wall of the air heater device. Air is also drawn intochamber 36 through filters 7-8 and the resistance to flow, or pressuredrop, created by filters 78 is sufficient to provide the desired orproper amount of cooling air flowing through chamber 35 for the desiredcooling effect on the heater outer walls.

Outlet duct 54 projects through and is secured to the rear wall ofcasing 39 by means of a circular angle member 82 secured to the outersurface of duct 54 and the inner surface of casing 39. A plurality ofconcentric tubes 83, 84 and 85 is provided with. tube 83 slidably fittedover tubular duct 54. Tube 83 is the central tube of the plurality. Abrace 86 is hooked at one end around the outer end of tube 85 and can bemounted at its other ,end to suitable building structure for supportingthe outlet end of the assembly of concentric tubes. A flue shield lineris mounted within tube 85 by suitable spacer mounting brackets. Tube 84projects through the liner. Two concentric flanges 89 and 90, eachconcentric with duct 54, are secured to the outer surface of the rearwall of casing 39 and project outwardly through rear wal1 19, as doesduct 54. Tubes 84 and 85 are slidably received over flanges 89 and 90respectively forming a telescoped assembly between tubes 83 through 85secured to duct 54 and flanges 89 and 90 by force fit.

Cross braces 92 and 93, illustrated as long bolts, impale each of tubes83 through 85 generally along diam eters thereof, bolts 92 and 93 beingillustrated as disposed along different angular dispositions withrespect to each other, e.g. at right angles to each other.

Bolts 92 and 93 also impale an inner tube member 94, suspending tube 94generally centrally within tube 83. Bolts 92 and 93 receive nuts attheir straight ends and serve to maintain general concentric dispositionof tubes 83 through 85 which are also supported concentrically byexhaust duct 54 and flanges 89 and 90. Attached to and extending partway across the end of tubes 83 there is provided a deflector member inthe form of a rigid fiap 95, the function of which will be more evidenthereinbelow. Deflector 95 is secured to the upper surface of the outerend of tube 83 by a flange portion welded to tube 83.

A chain 96 extends through small aligned holes in the lower wallportions of each of tubes 94 and 83 through 85. Chain 96 is heldgenerally taut and secured at opposite spaced ends by cotter keys 97which retain the chain in position by functioning as stops against theinner surface of tube 94 and the outer surface of tube 85. Chain 96 aidsin holding the tubes 94 and 83 through 85 in concentric disposition andprevents incorrect placement of the tubes during installation.

As gases are exhausted throughduct 54 there may be some leakage betweenduct 54 and the tube 83 telescoped thereover, the connectiontherebetween being a forced fit ,or sliding connection. For this reason,concentric tube 84 is provided surrounding tube 83 to conduct gaseswhich may leak through the connection outwardly away from the areaadjacent wall 20 and casing 39 where such gases may be carried into theair intake system and eventually be discharged into the room or buildingbeing heated. For like purpose, concentric tube is provided surroundingtube 84 to direct any gases which may leak between flange 89 and tube 84outwardly away from wall 20.

Disposed below the combustion gas exhaust system described above is thecombustion air inlet system which includes a tubular member 98telescoped and force fitted over a flange. 99. The flange 99 defines theinlet duct for air being drawn into chamber 44 for use by burner 45.Cross brace members 100 and 101, in the form of bolts and nuts, suspendinner tube member 102 generally concentrically within tube 98.

Cross brace members 92, 93, 100 and 101, in addition to functioning forbracing purposes also help to block passage of objects inwardly throughducts 54 and 99 during operation of the device or otherwise. Thecentrally mounted tubes 94 and 102 are also provided for preventingbirds from entering and building nests.

The purpose of the deflector 95 is to prevent reverse flow of combustiongases when the wind is blowing directly at the discharge end of tube 83.With wind blowing directly against the open ends of tubes 83 and 98,deflector 95 creates a cross flow of air which increases or aids thedischarge of combustion gases from tube 83 because the wind can enterinlet tube 98 easier than outlet tube 83.

The heater device may be conveniently installed by setting the device ona supporting surface at the desired location and connecting the burnerand electrical system in the usual manner to fuel line and thermostat.Means illustrated at 105 (FIGURE 3) are also provided for mounting thedevice in a position suspended from a wall, desirable where floor spaceis limited. Accordingly, each mounting 105 includes a circular hole 106in rear wall 20 of suflicient size to clear the head of a bolt 107 orscrew or the like. A slot 108, at least as wide as the shank of bolt 107and narrower than the head of bolt 107, extends upwardly from hole 106.A plurality of such mountings is provided, each at a different locationin rear wall 20, preferably near the top of wall 20. In installing,bolts 107 are secured into the wall at positions spaced in accordancewith the spacings of holes 105, With the heads of bolts 107 protrudingslightly. The heater is lifted to the wall and holes 105 are guided overthe bolt heads and the bolt shanks are directed into slots 106. Burnerand electrical connections, etc. are then made to the mounted device.

In operation of the device, motor 63 and burner 45 are started in theusual manner and air is drawn by burner 45 through intake duct 99 intocombustion air chamber 44, thence through burner, 45 and the resultingflame and combustion gases are ejected into combustion chamber 50 andare exhausted through ducts 53 and 54 and 83 exteriorly of the room orbuilding. Passage of air through chamber 44 serves to keep electricalsystem 68 cool. Meanwhile, fan 62 draws air from chamber 36 and forcesthe air through chamber 34 in heat exchange with furnace or combustionchamber 50 and thence outward through grill members 72 for direction ofair into the room as desired. The air is heated in chamber 34. Fan 62draws air into chamber 36 through louvers 77 and thence in separatepaths to chamber 36, one path through filter 78 and the other paththrough the air space 35 beneath the surfaces of walls 12, 14, 20 and29. Thus, there is provided a separate flow system, including two flowpaths, for drawing air from a room and heating and returning the air anda separate flow system for drawing air from exteriorly of the room forburning fuel by the burner for heating the air by heat exchange with thefirst flow path, the combustion gases being exhausted exteriorly fromthe stood in the air heater illustrated therein that the portions notshown in detail are similar to those already described above withrespect to FIGURES 1 through 3. The air heater, as shown in FIGURE 5, isparticularly adaptedas a free-standing air heater for connection to achimneysuch as illustrated at 109. For this purpose, a stack 110 isprovided of proper length and direction to extend from outlet 54 ofchamber 53 to chimney 109. Stack 110. is adapted to connect at its openstack end with chimney 109 for venting flue gas thereto in the usualmanner. In the illustrated form, a furnace exhaust branch line 112 ofstack 110 connects with flange 89 to enclose out-let duct 54. An end cap111 is provided on the lower end of stack 110 to seal against escape ofexhaust gases. Damper branch 113 is also provided branching fromstack-.110 and a damper mechanism 114, of conventional design, isdisposed across damper branch 113 at the extended end thereof. Damper114is designed to swing only inwardly from its closed position andfunctions as a draft damper.

Damper 114, inclosed position, prevents exhausting of combustion gasestherefrom.

A bracing or mounting bracket 115 is provided secured between rear wall19 and stack 110 to hold stack 110 in proper supported position.

A mufller cap 118 is'disposed over an inlet duct 119 fitted on flange99. Muffler cap 118 includes a dome-like shell 120 having a peripheralflange or rim 121. Spacing brackets 122 are secured by welding or thelike to flange 121 at one end and are machine screwed or bolted tocasing rear wall at the other end to support mufller cap 118 spaced fromwall 20 a suflicient distance to permit inletof air for combustionpurposes. Cap 118 includes a lining of insulation 123, 'e.g. fiberglassor the like, which functions for sound absorption purposes. Cap

118 decreases burner sounds emitted from the combustion chamber orburner inlet while still permitting free-flow of inlet combustion air.

The free-standing form of air heater illustrated in FIG- URE 5, includesapair of channel-shaped tapered leg members 126, one along each sideedge of the bottom wall 26 of the furnace casing, forsuppo-rting the airheater from a floor or the like. The channel-shaped tapered legs 126include outward projecting flanges, 127 from each edge thereof disposedagainst wall 26. Flanges 127 are secured to bottom wall 26 by machinescrews,

welding or the like. It will be noted in FIGURE 5. that the taper oflegs 126 provides a bearing surface at each '55' rear corner of thecasing for supporting the casing from a surface therebelow, but thetaper of the legs-is away from bearing engagement with the surface atthe front of the air heater casing. At the front of each leg 126 thereis provided a level adjusting support 128 in the form of a foot with athreaded 'shankor leg extending upwardly therefrom and, threadedthrougha nut -member' which in turn is secured through the bottom wallof channel 126. It will be apparent that the adjusting members areadjustable to change the height of each front corner of the casing bythreading the members in one .direction or the other, as desired orneeded, resulting in raising or lowering each or either of the rearcorners of the air heater.

We claim:

1. An air heater, comprising: a housing having an exterior wall definingat least an air inlet and an air outlet for said air heater; meansdefining an air heating chamber within said housing so that intake airis directed through separate branch flow paths from said inlet, one ofsaid flow paths defining a blanket of insulating air between saidexterior wall and said heating chamber, the other of said flow pathsdefining a generally direct route from said inlet, through said heatingchamber, to said outlet; a blower mounted in said housing for drawingair in from a room, through said separate flow paths'and discharged asheated. air back to the room; and a filter in said other flow pathadjacent said inlet creating a resistance to the flow of air throughsaid other. flow path to insure'the flow of air induced by said'blowerinto said'insulating flow path while filtering air throughsaid otherflow path.

2. An air heater, comprising: a housing having'an exterior wall definingat least an air inlet and anaair outlet for said air heater; meansdefining an air heating chamber within said housing adjacent to and incommunication with said air outlet; means defining a combustion chamber1 communicating with said combustion chamber for burning fuel therein;means defining an air inlet chamberwithin said housingadjacent to and incommunication'with' said air inlet and in communication'with said airheating chamber; said exterior wall, heating chamber and inlet chambercomprising means for directing intake air through separate branch flowpaths from said inlet, one of said flow paths defining a blanket ofinsulating air flowing from said air inlet between said exterior walland at leasta portion of said heating chamber to said inlet chamber, theother of. said flow paths defining a. generally ,direct route from saidinlet through said inlet chamber and said heating chamber to saidoutlet;'a blower in said other flow path downstream from said inletchamber for drawing air in from a room, through said separate flow pathsand discharged asfheated'air back to the room; and a filte'r' in saidother flow path downstream from said inlet creating a resistance to theflow of air through said other flow 'path to insure the flow of airinduced by said blower into said insulating flow path while filteringair through said other flow path.

3. In an air heater having a casing with walls and in whichintake air isdrawn in from a room through an inlet,

heated in a heating chamber and discharged as heated air back to theroom, the improvement which comprises means within the casing fordirecting the intake air. con-1+ ing from said inlet through separateflow paths, one of said flow paths defining a blanket of insulating airflow-' ing along the interior surfaces of said casing walls, the otherof said flow pathsdefining a generally direct route from the room to theair heating chamber, and a filter.

in said other flow path adjacent the inlet creating a resistance to theflow of air through said otherflow path to insure the flow of air intosaid insulating flow path while filtering air through said other flowpath.

' 4. The air heater of claim 3 stream from said inlet. 7 V a l 5. An airheater, comprising: a. housing having an ex terior wal l defining atleast an air'inlet and-an air outlet". for said air heater;meansdefining'an air'heating chamber 4 within'said housing adjacent to and incommunication with said air outlet; means defining an air inlet chamberwithin said housing adjacent to and in communication with said air inletand in communication with said air heating chamber; said exterior wall,heating chamber and inlet chamber comprising means for directing intakeair through separate branch flow paths from said inlet, one

of said flow paths defining a blanket of insulating air flowing fromsaid air inlet between said exterior wall'and at least a portionof saidheating chamber to said inlet.

chamber, the other of said flow direct route from said inlet. throughsaid inlet chamber and said heating chamber tosaid outlet; a blower'insaidother filter in said other flow path downstream fromsaid inletwherein said filter is down:

paths defining a generally creating a resistance to the flow of airthrough said other flow path to insure the cflow of air induced by saidblower into said insulating flow path while filtering air through saidother flow path.

5 References Cited by the Examiner UNITED STATES PATENTS 2/1935Cornelius 1261-10 9/1935 Sadwith 126 1-10 3/1938 Bard 126 -110 10 5/1938Williams 62-259 Sorsoleil 126-1-10 Ryder et 211. t 126-116 X Watts126.1'10 Thompson et al 98-612 Roberts 9840 Humphrey 126110 Mueller126-4 10 Chamberlain 98---62 Martz 1268S JAMES W. WESTHAVER, PrimaryExaminer.

1. AN AIR HEATER, COMPRISING: A HOUSING HAVING AN EXTERIOR WALL DEFININGAT LEAST AN AIR INLET AND AN AIR OUTLET FOR SAID AIR HEATER; MEANSDEFINING AN AIR HEATING CHAMBER WITHIN SAID HOUSING SO THAT INTAKE AIRIS DIRECTED THROUGH SEPARATE BRANCH FLOW PATHS FROM SAID INLET, ONE OFSAID FLOW PATHS DEFINING A BLANKET OF INSULATING AIR BETWEEN SAIDEXTERIOR WALL AND SAID HEATING CHAMBER, THE OTHER OF SAID FLOW PATHSDEFINING A GENERALLY DIRECT ROUTE FROM SAID INLET, THROUGH SAID HEATINGCHAMBER, TO SAID OUTLET; A BLOWER MOUNTED IN SAID HOUSING FOR DRAWINGAIR IN FROM A ROOM, THROUGH SAID SEPARATE FLOW PATHS AND DISCHARGED